Horrific violence continues to spread across Gaza this week, where an Israeli air and ground offensive against the Islamist group Hamas has killed more than 700 people — most of them Palestinian civilians, and many of them children. Both the United Nations and the US, Israels main ally, have called for a cease-fire, though neither side has shown any sign of relenting. This months fighting marks the third time in five years that Israel has launched a large-scale military operation in Gaza, a small enclave on the Mediterranean that Hamas has governed since winning a majority in the 2006 Palestinian parliamentary elections. Ten days later, Israel launched a ground invasion aimed at crippling the vast network of underground tunnels that Hamas uses for weapon storage and to launch attacks.